Braking apparatus



April 9, 1935- E. E. HUFFMAN BRAKING APPARATUS I.

Filed Aug. 2B, 1931 Fig. 1

r O t n w m f )ll/Ml 5 n. 9 2 m W 7. 2 A. f h/Af s, 3 aww liz il Wl 6 ing pressure.

Patented pr. 9, Y1935 nmz ' UNITED STATES PATENT OFFICE Application August 28,

12 Claims.

My invention -relates to braking apparatus and particularly to power actuating means for the compressor element of braking apparatus of the type in which iluid is employed to transmit brak- One of the objects oi my invention is to so relate the power actuating means with the manual means for actuating the compressor that a part of said manual means, preferably the brake pedal, will constitute a control element for determining the braking pressure applied by the power source, whereby, in the event of failure of the power means, the operator may readily apply the brakes solely by-pedal pressure in the usual manner without any preliminary movements or manipulations of mechanism.

Another object of my invention is to provide control means for the power actuator whereby the operator will feel the braking pressure in that the power applied reacts on the pedal in proportion to the magnitude of vsaid power.

Further objects and advantages of the invention will appear from the following description:

In the accompanying drawing Figure 1 illustrates an embodiment of my invention, the fluid compressor and the source of power (pump) being rhown in cross section and a wheel braking mechanism being shown diagrammatically; Figure 2 is a cross sectional view on the line 2--2 of Figure l; and Figure 3 is an enlarged cross sectional view of the pedal operated valve, constituting the power controlling means.

Referring to the drawing, I indicates a casting mounted on the vehicle and so formed as to provide a reservoir 2 in the upper part thereof and two aligned cylinders l and 5 in .the lower part. The space or chamber 3 between the cylinders is in continuous communication with the reservoir 2 -through the elongated opening 6 through which the manually actuable operatin arm IS extends.

The cylinder I constitutes the compressor or master cylinder of the braking apparatus whereby uid pressure is transmitted to the uid of motors at the wheels, one of these motors being diagrammatically indicated at 8. i

Since my invention does not relate to details of the hydraulic mechanism which directly actuates the brakes, it isunnecessary to give more than a brief description of particular mechanism for this purpose illustrated in the drawing. lThe liquid pressure is produced by piston 'I operating in the cylinder I, this piston being shown in the drawing in its retracted position in which position the piston sealing cup 9 is at the rear of 1931, Serial No. 559,820

(Cl. GIF-54.6)

the compensating opening I II through the wall of the cylinder and the latter, therefore, is in liquid communication with the reservoir 2. I I indicates a differential valve at the forward end of the cylinder which permits liquid to be freely 5 discharged into the brake line but requires a predetermined pressure to open it to allow the liquid to return to the master cylinder, thus maintaining such minimum pressure in the brake lines.

The piston 'I is also provided with passages I2 1Q whereby liquid may pass from the rear of thepiston and pass the sealing cup into chamber l, should there be such a loss of liquid upon brake application that the piston could not otherwise return to 01T position without creating sub-at- 15' mospheric pressure in the brake line tending to draw air into the system at the wheel cylinders.

In addition to the parts Just described, the mechanism illustrated embodies a known type of manual piston actuating means comprising 20 foot pedal I3, mounted on shaft I4 journaled in the walls of reservoir I. The pedal is provided with return spring I5 and is adapted to actuate the arm I6 also mounted on the` shaft I l and vextending into operative rotation with the rear 25 of piston 1. This arm is bifurcated at its'lower end as shown in Figure 2 .to permit the thrust member. II, carried by piston I8, to engage the center of piston 1. Piston I8 is provided with a sealing cup I9 and reciprocates in cylinder 5. 30 'I'his cylinder and piston constitute thev fluid motor by means of which the power source actuates the compressor piston.

It will be noted that in the construction described tlie piston 1 may be actuated in pressure applying direction by means of foot pedal without thereby moving the piston I8.

In addition to the cylinder 5 and its piston I8, the power actuating mechanism oi.' my .invention comprises a fluid pump 20 for supplying uid under pressure to the cylinder 5 and valve'mechanisxn 2| for controlling the magnitude of this pressure. The pump may conveniently be of the well known gear type as illustrated and while it maybe driven by seperate source of power such as electric motor, or by the vehicle engine, I prefer that it be driven from an element of the vehicle such as the propeller shaft or a portion of the transmission mechanism which is in operation when the vehicle is moving whether or not the vehicle power source is in'operation. Thus the pump may deliver power for actuation of the brakes when the Vehicle is coasting in the condition of being either entirely disconnected-from esA the engine or being in what is commonly referred to-as free wheelingf connection therewith.

'I'he delivery conduit 22 of the pump yis connected with cylinder 5 and the supply conduit 2l is in communication with the liquid reservoir 2, preferably at a point above the level of the cylinder 4. The wall of cylinder 5 is provided with a passage 24' so located that the cylinder will always be in communication (through the .valve mechanism 2 I) with` the reservoir 2.

The valve mechanism illustrated comprises tube 25 forming an extension oi e 2| and provided with an internal valve seat 26 and with an extension 21 which carries the valve 2l, the valve control spring 29, and the plunger 3l by means of which pressure may be applied to the valve through the spring. Fully retracted positin of the plunger is determined by pin 8| carried by the plunger and projecting into the elongated slot in extension 21 as shown. When the valve is unseated during the-operaticm of the pump, the liquid passes from the tube 25 to the reservoir 2, through the lateral openings 32 in the tube extension 21. The'hub of the piston operating arm il is provided with upward extension 33 which carries adjustable abutment plate 34 to engage the valve controlling plunger Il.

Referring to the operation of the apparatus-de.- scribed, the brake system, pump and reservoir are supplied with a suitable brake operating fluid (a mixture oi castor oil and alcohol, for example) and assuming that the vehicle is in motion, pump 20 circulates liquid from the reservoir to the .dylnder land through the valve 2l back to the reservoir.' The valve 2l is preferably biased to fully closed position by means of spring 2l, but this spring pressure is very light when the brake pedal is in retracted position and therefore the liquid pressure built up in the cylinder 5 by the pump in forcing liquid past the valve 2l is'insuftlcient to overcome the tension of the usual piston returning spring 35 of the master cylinder and, therefore, the piston 1 will not be moved and no braking pressure will be built up in the braking system.

Y If the operator desires to apply the brakes, the

4may be sc related, that the arm. will never contact with the piston 1 during motion in brake applying direction except when more, ,brahng pressure is desired than the pump produces under the pressure' onthe valve k28 which will be produced by'any movement of the foot pedal which does not bring arm Il into engagemen .with the piston 1.

If it should be desired that al1 very light-braking pressures be applied solely by thepower of v the operator and without thece of the pump pressure,-the valve controlling parts will be soadjustedthatcertainminimumoftravelofpistonl must occur before spring-29 is to a degree which will cause any operative pressure to beproduced in the chamber 5. In all cases, however, it will be considered desirable that the minimum pressure of spring 2! (or the effective area of the e from the cylinders tothe reservoir in relation to pump capacity) be such that piston il will be caused to follow piston 1 whereby there will be no lost motion be.

tween the pistons to be taken up when the piston It becomes operative to .assist braking action. It will usually be desired to so adjust the mechanism that after piston -IO becomes eective to apply pressure, lt will supply all of the braking pressure required `whereby the operator will not normally exert more eifort thann v A to compress the valve spring to the proper degree to secure the desired braking action.

The pedal pressure required to cause the pump to produce pressure on piston Il will be proportional to the produced pressure and, therefore,

braking pressure being applied and can as readily control this pressure as if he were himself directly applying all of the braking pressure.

As will be apparent, the structure described becomes automatically an ordinary manual braking system, in the event of any failure of the power mechanism, without the necessity of any movements or manipulations by the operator.

Upon release of the brahe pedal by the operator, thespring Ilcausesthearm Il toimmediately return to non-operative position and all pressure on valve 2l is released except the #adjusted minimum pressure, if any, and since the valveopeningmaybereadilymadesuchasto 'the operator will have the "feel" of the amount of g permit liquid to discharge from the cylinder i' as rapidly as it ilows back' to the master cylinder, the power apparatus does not interfere with quickas shown, the vehicle operator will be warned to supply additional liquid to the rervoir before the liquid has been so far exhausted that the brakes are no longer even manually operable, in that the power system will have rst ceased to function. v

Itwillbeunderstoodthatthediameterofthe cylinderlmaybelargerorsmallerthanthatof the master cylinder depending upon the maximum brakingpressuredesiredandthemaximumpressure which the form of pump is capable of producing at a selected speed; and, also, that onlyaverysmallgearpumpwouldbereqmred even for the largest vehicles. y

The apparatus described permits substantially theiulleifortoftheoperatorto'beaddedtothe maximum power of the pump in creating braking pressure for stops. l

Havingfullydescribedmyinvention, whatI claimasnewanddcsiretoseenrebyLetters Patent of the United' Btates'is:

l. In iluid actuated braking apparatus, a compressor for creating fluid pressure to apply a brake, a fluid motor for actuating said compressor, apumpforcreatingpressurein said motor, avalvefor controllingsaid,andmanual means capable oi actuating the compressor and movable independently of the movable member of the iiuld motor, said manual means controlling said valve independently of any movement of the movable member of the iluid motor to progressively vary the pressure which may be produced in the iluid motor in accordance with the extent of movement oi' said manual means.

2. In fluid actuated braking apparatus, a compressor for creating nuid pressure to apply a brake, power means for actuating the compressor, manual means for actuating the compressor, and capable of movement independently of the movable member of the power means, and control means operated by the manual. means and adapted to cause the magnitude of the power applicable to the compressor by the power means to progressively increase in response to advance of the manual means in its operative path of travel.

3. In iluid actuated braking apparatus, a compressor for creating iiuid pressure to apply a brake, power means for actuating the compressor, manual means capable of actuating the compressor and comprising a brake pedal, the actuated element of the compressor being free to advance in brake applying direction independently of the brake pedal, and control means operated by the brake pedal and adapted to cause the magnitude of the power applicable to the compressor by the power means to be lower at a position intermediate the limits oi' travel oi the pedal than in a position in advance of said last named position, said control means being unaffected by movement of the actuated element of the compressor independently of movementof the brake pedal.

4. In iluid actuated braking apparatus, a compressor for creating pressure comprising a cylinder and piston therein, a iluid motor comprising a cylinder and a piston in alignment with the iirst named piston and having a member in thrust engagement therewith, manually operable means for actuating the rst named piston, said manual means being movable independently of the piston of the fluid motor, means for supplying nuid under pressure to said fluid motor, a pressure relief valve for controlling the magnitude of said pressure, and means movable by the manual brake applying means for controlling the pressure required to open said valve, said means being unaffected by any movement of the movable member of the fluid motor independently of movement of the brake pedal.

5. In iluid actuated braking apparatus, a liquid reservoir, a compressor cylinder and piston therein, said cylinder being in communication with said reservoir when the piston is in retracted position,

ing its pressure side in communication with theiluid motor and with the reservoir through said passage, manual means for actuating the compressor piston, a valve for said passage, resilient means for biasing said valve toward closed position, and means for controlling the pressurev of said resilient means in accordance with the position of said manual means.

6. In apparatus for creating fluid pressure for the actuation of fluid operated brakes, a member for applying pressure to the iiuid, a uid motor for applying pressure to said member, manual means for applying pressure to said member and comprising a brake pedal, said pedal being movable indepen iently of the movable member of the fluid motor, a power operated pump connected to said iluid motor, a pressure relief valve for said motor, and means actuated bythe brake pedal independently oi any movement of the movable member of the iiuid motor for controlling the pressure required to open said valve.

7. In iiuid actuated braking apparatus-a liquid reservoir, a compressor cylinder beneath the reservoir and a piston in said cylinder, a liquid motor comprising a cylinder and a piston in alignment with the compressor piston, means for transmitting the motion of the liquid motor piston to the compressor piston in pressure applying direction only, a liquid chamber between said pistons and in communication with the reservoir, a manually actuable member extending into said chamber and to a position at the rear of the compressor piston to be engageable therewith, a brake pedal for operating said member, means forming a passage connecting the liquid motor cylinder with the reservoir, a relief valve in said passage, a power actuated liquid pump having its delivery side connectedto the motor cylinder and its inlet connected to the liquid reservoir, resilient means tending to close the Valve, and vmeans governed by the position of the brake pedal for varying the resistance of the resilient means to the opening movement of the valve.

8. In iiuid actuated braking apparatus, a compressor for creating iiuid pressine to apply a brake, power means for actuatingthe compressor, manual means capable of actuating the compressor and comprising a brake pedal, the actuated element of the compressor being movable in brake applying direction independently of the manual means, and means for progressively varying the magnitude of the pressure applied by the power means in accordance with the extent of movement oi`the brake pedal, from its o position.

9. In apparatus for creating liquid pressure for the actuation of liquid operated brakes, a member for applying pressure to the liquid, a liquid motor for applying pressure to said member, manually operable means for applying pressure to said member, said manual means being movable independently of the movable member of the motor, a power operated pump connected to circulate liquid through said liquid motor, a pressure adjusting valve in the discharge passage from said motor capable of varying the liquid pressure applicable by said pump to said motor, and manually operable means for controlling said valve independently of any movement of the movable member of thev liquid motor.

10. In apparatus for creating liquid pressure for the/actuation of liquid operated vehicle brakes, a member for applying pressure to the liquid. a liquid motor for applying pressure to said member, manually operable means for applying pressure to said member, said manual means being movable independently of the movable member of the motor, a pump and connections operable to continuously circulate liquid through said liquid motor while the vehicle is in motion, a pressure adjusting valve in the discharge passage from said motor capable of varying the liquid pressure applicable by said pump to said motor, and manually operable means for controlling said valve independently of any movement of the movable member of the liquid motor. y

11. In apparatus for creating iiuid pressure fior the actuation of iluid operated brakes, a member for applying pressure to the fluid, a iiuid motor forl applying pressure to said member, manne? means for applying pressure to said member and comprising a brake pedal, a power operated pump connected to said iiuid motor, a pressure relief valve for said motor, and adjustable connections between the valve and brake pedal for varying to the movemeniaf the pedal..

12. Power means for actuating vehicle brakes comprisinga.llmiidmntor,apumpundconnections for continuously circulating liquid through said motor while the vehicle is in motion, a pressue adjusting valve in the discharge passage from said motor for varying the liquid pressure applicable by said pump to said motor, seid valve 1o being biased-to closed position but being so mountedthatthepressureoftheliquidinthediseharge etendstomaintainthevalveinopmposition. andmanualmeansior-actuating thebrakes andforapplyingpreasuretothevalvetourgeit toward closed position, saidmanual means being movable to actuate the brakes without moving EDWIN E. HUF'FMAN. 

